This is a program assessing the sleep of healthy male and femal persons between the ages of 50-70 years. The structure of sleep is measured by electroencephalograms, the patterns of sleep by home sleep diaries and the subjective aspects by nightly post sleep ratings and by questionnaires. The interrelationships among these measures and their relations to an extensive battery of cognitive and personality measures are under study. Normative and inferential statistics are used to compare these data between genders and age groupings. Subpopulations of retirees and persons with extensive shift work experience are being used to determine effects of these variables on sleep in older populations. Experimental studies exploring the prominent characteristics of night time arousal are being conducted. The underlying purpose of this program is to provide baseline data in healthy aging subjects for clinical purposes, to aid in comprehending the effects of age per se on the sleep process, and to develop ameliorative procedures relative to night time arousals.